Piezoelectric resonator element, piezoelectric resonator, piezoelectric oscillator, resonator gyro element, resonator gyro sensor, and electronic apparatus

Abstract

A piezoelectric substrate includes vibrating arms, a base portion to which one end portion of each vibrating arm is connected, spindle portions formed in the other end portion of each vibrating arm, formed to have a large width, and having first groove portions formed therein, and second groove portions that are formed along the resonator center line of each vibrating arm, and flexure-torsional combined resonator is excited. A piezoelectric resonator element has flexural resonator of flexure-torsional combined resonator that is excited as its principal resonator and sets the cutting angle of the piezoelectric substrate, the widths and the depths of the first groove portion and the second groove portion, and the thickness of the vibrating arm such that the frequency-temperature characteristics represent third-order characteristics with respect to the temperature.

What is claimed is: 
     
       1. A resonator element comprising:
 a base; and 
 a pair of vibrating arms that extends from the base in a first direction in a plan view, the vibrating arms are located next to each other in a second direction perpendicular to the first direction, the vibrating arms performing flexure-torsional combined vibrations, each of the vibrating arms having a spindle portion and an arm portion, the arm portion being sandwiched by the base and the spindle portion, wherein 
 the spindle portion has a first surface and a second surface that is opposite to the first surface, and a first groove is provided in at least one of the first and second surfaces, 
 the arm portion has a third surface, which is continuous with the first surface, and a fourth surface, which is continuous with the second surface and opposite to the third surface, a second groove is provided in at least one of the third and fourth surfaces, and the second groove extends along the first direction, 
 each of the first and second grooves overlaps with an imaginary line passing through a center of gravity of each of the vibrating arms in a plan view, 
 the first and second grooves are separately provided, and 
 an electrode is provided on the first surface, the second surface, an inner surface of the first groove, a side surface that interconnects the third surface and the fourth surface, and an inner surface of the second groove. 
 
     
     
       2. The resonator element, according to  claim 1 , wherein
 a width of the spindle portion in the second direction is larger than a width of the arm portion in the second direction. 
 
     
     
       3. The resonator element, according to  claim 1 , wherein
 the resonator element is configured with a quartz crystal plate, and 
 a normal line of a principal surface of the quartz crystal plate is inclined by an angle within a range of 0 degree to −15 degrees with respect to an optical axis of a quartz crystal of the quartz crystal plate. 
 
     
     
       4. The resonator element, according to  claim 1 , wherein
 the first groove is configured with a plurality of grooves that are separately aligned to each other in the first direction. 
 
     
     
       5. The resonator element, according to  claim 1 , wherein
 the first groove extends from an outer edge, which is opposite to the arm portion, of the spindle portion toward a center of the spindle portion. 
 
     
     
       6. The resonator element, according to  claim 1 , wherein
 a width of at least a part of the first groove in the second direction is larger than a width of the second groove in the second direction. 
 
     
     
       7. The resonator element, according to  claim 1 , wherein
 the base includes:
 a base main body from which the vibrating arms extend; 
 a connecter that is provided at an edge of the base main body located on an opposite side with respect to the vibrating arms in the plan view, a width of the connecter in the second direction is smaller than a width of the base main body in the second direction; and 
 a support arm that extends from the connecter and that is spaced apart from the base main body. 
 
 
     
     
       8. A resonator comprising:
 the resonator element according to  claim 1 ; and 
 a substrate on which the resonator element is mounted. 
 
     
     
       9. An oscillator comprising:
 the resonator element according to  claim 1 ; 
 an IC that drives resonator element. 
 
     
     
       10. A gyro sensor comprising:
 the resonator element according to  claim 1 . 
 
     
     
       11. An electronic apparatus comprising:
 the resonator element according to  claim 1 . 
 
     
     
       12. A resonator element comprising:
 a base; and 
 a pair of vibrating arms that extends from the base in a first direction in a plan view, the vibrating arms are located next to each other in a second direction perpendicular to the first direction, the vibrating arms performing flexure-torsional combined vibrations, each of the vibrating arms having a spindle portion and an arm portion, the arm portion being sandwiched by the base and the spindle portion, wherein 
 the spindle portion has a first surface and a second surface that is opposite to the first surface, and a first groove is provided in at least one of the first and second surfaces, 
 the arm portion has a third surface, which is continuous with the first surface, and a fourth surface, which is continuous with the second surface and opposite to the third surface, a second groove is provided in at least one of the third and fourth surfaces, and the second groove extends along the first direction, 
 each of the first and second grooves overlaps with an imaginary line passing through a center of gravity of each of the vibrating arms in a plan view, 
 the first groove extends from an outer edge, which is opposite to the arm portion, of the spindle portion so as to integrate with the second groove, and 
 an electrode is provided on the first surface, the second surface, an inner surface of the first groove, a side surface that interconnects the third surface and the fourth surface and an inner surface of the second groove.